A Mogo man and a Western Sydney seafood restaurant owner have been arrested following the seizure of more than 3300 illegal South Coast abalone and 40 kilograms of shark fin, the largest abalone haul in more than 20 years.

The seizure followed a joint operation by the Department of Primary Industries (DPI) Fisheries and NSW Police investigating illegal abalone trafficking from the South Coast to unlicensed Sydney-based receivers.

The raid, which took place in the early hours of Sunday morning, is estimated to be worth more than $57,000.

Abalone is listed as a priority species and is an indictable species under the Fisheries Management Act DPI director of fisheries compliance Patrick Tully said.

“Following an extended and targeted surveillance operation by fisheries officers from the Statewide Operations and Investigations Group, a 59-year-old man from Mogo NSW was intercepted in the western Sydney suburb of Berala,” he said.

“It will be alleged the man delivered a consignment of illicit abalone to a residence in Berala.

“Shortly after leaving the house, the man’s vehicle was intercepted with the assistance of NSW Police where 439 abalone in the vehicle were seized along with documentation allegedly relating to abalone trafficking.

“The man’s vehicle was seized and he was arrested and taken to Auburn Police Station.”

DPI fisheries investigators executed a search warrant on the house at Berala and seized 2870 alleged illegal abalone weighing approximately 300 kilograms.

Fisheries officers also located and seized 40 kilograms of shark fin. Investigations into the origin of the shark fin are continuing.

An associated Western Sydney seafood restaurant was also raided, with officers seizing a further 645 prohibited size abalone.

“A 62-year-old man, who is also the owner of a Western Sydney seafood restaurant, will face a range of charges including trafficking in fish which carries a maximum penalty of 10 years imprisonment,” Mr Tully said.

NSW Police marine area commander detective superintendent Mark Hutchings said NSW Police work closely with DPI to target the illegal poaching of marine life, in all its forms.

"We have a strong relationship with NSW DPI Fisheries officers fisheries and will continue to work closely with them as a partner agency to detect the trafficking and illegal sale of abalone, in particular,” Det Supt Hutchings said.

"Anyone with information that could assist police regarding their investigations into these incidents is urged to contact Crime Stoppers on 1800 333 000.”

Apart from the maximum of 10 years jail the men face, individuals convicted of trafficking abalone can also receive a fine up to 10 times the market value of the abalone.

“The market value of the abalone seized is worth more than $57,000,” Mr Tully said, making a fine of more than $570,000 possible.

“If you are offered to purchase cheap abalone or from an unlicensed commercial fisher you could be involved in the trafficking of illegal abalone.

“The quality, handling and hygiene of illegal abalone is unsafe and doesn’t follow the strict guidelines in place by NSW Food Authority for seafood, so not only could you get a criminal record and face large fines, but you could become very sick from eating it.

“The only way to guarantee the quality of abalone, is to buy it from a reputable seafood retailer.”

Both men are expected to face court in the near future.

Anyone with information on suspected illegal fishing activity is urged to contact their local Fisheries Office or call the Fishers Watch phone line on 1800 043 536.